bDivision of Public Health and Biostatistics, Office of Food Defense, Communication and Emergency Response, Center for Food Safety and Nutrition, U.S. Food and Drug Administration, College Park, Maryland, USA

bDivision of Public Health and Biostatistics, Office of Food Defense, Communication and Emergency Response, Center for Food Safety and Nutrition, U.S. Food and Drug Administration, College Park, Maryland, USA

cDivision of Foodborne, Waterborne and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA

dDivision of Microbiology, Office of Regulatory Science, Center for Food Safety and Nutrition, U.S. Food and Drug Administration, College Park, Maryland, USA